Apparatus for investigating earth formations



Feb. 2, l1960 FIG. l

R. Q. F IELDS APPARATUS FOR INVESTIGATING EARTH FORMATIONS Filed Marchl2, 1956 @www HIS ATTORNEY United States Patent "O FOR INVESTIGATINGEARTH FORMATIONS Application March 12, 1956, Serial No. 570,764V

7 Claims. (Cl. Z55-1.4)

APPARATUS This invention relates to apparatus for investigating earthformations and, more particularly, pertains to a new and improvedcore-taking device for obtaining a sample of earth formation material.

In present practice, cores or samples of earth formation material may beobtained by projecting a hollow core-taking tube or barrel into aformation by means of a gun. For example, the gun may be lowered througha borehole drilled into the earth to the level of a formation to beinvestigated and then discharged. The core barrel thus is impelledtoward the sidewall of the borehole and is embedded in the formation,its hollow interior thereby being filled with formation material.Usually the core barrel is secured to the gun by one or more flexibleconnections. Thus, by raising the gun, the core barrel with its sampleis drawn from the formation and can be brought to the surface of theearth for examination.

To facilitate recovery of a core, it has been proposed that thecore-barrel be provided with a separable forward portion in the form ofan annular ring. In particular, this ring may have a slightly greaterdiameter than the core barrel, as disclosed in U.S. Patent No. 2,288,210to Marcel Schlumberger. v

It is an object of the present invention to provide new and improvedcore-taking device of the general type disclosed in the aforementionedSchlumberger patent.

Another object of the present invention is to provide a new and improvedcore-taking device in which separable forward and body portions may beconveniently maintained in fixed spatial relation to one another, butare immediately separable after the device is embedded in a formationunder investigation.

Yet another object of the present invention is to provide a new andimproved'core-taking device including separable portions which, prior toembedding in a formation, are in a relatively stable, unitary assemblythereby minimizing the possibility of inadvertent separation.

A further object of the present invention is to provide a new andimproved core-taking device which is simple and inexpensive to constructand yet is entirely efficient and reliable in operation.

Apparatus for investigating earth formations according to the presentinvention comprises core-receiving and formation-penetrating membersdisposed adjacent one another and adapted to be impelled toward theformation and embedded therein. A hollow retainer of resilient materialreceives portions of each of the corereceiving and formation-penetratingmembers to maintain them in essentially fixed spatial relation` to oneanother. However, `the retainer is releasable from at least one of themembers thereby to permit withdrawal of the core-receiving member fromthe formation' while the formation-penetrating member remains embeddedtherein. v t r The novel Ifeatures' of the present invention 'aref setYforth with particularity in the `appended claims. The

barrel 18 and cutting ring 24.

.present invention, both as to its organization and manner of operation,together with further objects and advantages thereof, Vmay best beunderstood by reference to the following description taken in connectionwith the accompanying drawing in which:

Fig. 1 is a cross-sectional view of apparatus for in- Vestigating earthformations embodying the presentl invention taken in a planeperpendicular to the axis of a borehole in which the apparatus isdisposed, andv illustrating the apparatus in one condition of operation;and

Fig. 2 is a view similar to Fig. 1, but illustrating the apparatus inanother condition of operation.

In Fig. 1 of the drawing there is shown a gun block 10 disposed in aborehole 11 Iopposite a formation of interest 12. Usually borehole 11contains a drilling mud 13, however, the present inventiony may beemployed in either dry or mud-filled boreholes.

Into gun block 10 extends a cylindrical bore 14 followed by a powderchamber 15 which terminates short of the rear surface of the gun block.Chamber 15 contains an appropriate propellant 16 and bore 14 receives agenerally cylindrical sample-taking projectile 17 constructed inaccordance with the present invention. Al-

though not illustrated, gun block 10 may contain additional projectilesin respective bores distributed along a vertical axis for the gun block.'Y l Projectile 17 is comprised of a substantially cylindrical, hollow,core barrel 18 provided with a rear or bottom closure 19 and adaptedrtobe impelled toward the formation 12 along a longitudinal axis 20 of thecore barrel. Core barrel 18 has a forward end 21 lying in a planeperpendicularto axis l2l)V and which, together with a portion of anoutercylindrical surface portion 22 defines a seat. Cylindrical surface` 22is provided with an annular recess 23 disposed in the vicinity offorwardend of the core barrel. I

A substantially cylindrical formation-penetrating member or cutting ring24 includes a rearward portion25 provided with a cylindrical recesscooperating withand engaging the seat 21, 22 of the corefbarrel. VInaddition, cutting ring 24 has an external surface 26 'of generallyfrusto-conical configuration extending Y Aforwardly from the rearwardportion 25 and inwardly toward. longitudinal-Yaxis 20. Surface 26terminatesY at the forward end of a cylindrical inner surface 27 for'cutting ring Y24 to defineA a cutting edge 28. Inner surface 27conforms vgenerally Ato a cylindrical innerrsurface 29 of core barrel18. Y

Preferably, cutting ring 24 has a portionrof a diameter D1 which islarger than the diameter D2 of core barrel 18. Thus, a portion of thecutting ring has a cross-sectional area in a plane perpendicular to axis20 larger than the cross-sectional area in a similar plane of thecore-barrel.

A substantially cylindrical hollow retainer 30 of resilient material,such as rubber, receives portions of core inner surface 31 providedwith. a ridge 32 extending inwardly into recess 23 of the core barrel.VIn addition, the retainer has an inner surface portion 33 conformingtoand engaging at least a portion of the external surface 26 ofgenerally frusta-conical configuration of the cutting ring. Accordingly,the core barrel and the cutting ring are maintained in essentially xedspatial relation to one another. The retainer further includesv aforward surface 34, disposed in a plane substantially perpendicular tothe longitudinal axis 20, adapted to engage formation material.v

Appropriately connected Yto opposite sides'of core'barrel 18, are a pairof flexible retrieving wires 35 and 35'. These wires are formed intocoils 36 and 37 which are dis Patenti-.d rgb. 2,1960

Retainer 30 includes an posed in respective openings 38 and 39 in gunblock 10U and their remaining ends are appropriately connected to' thegun block.

From an inspection of Fig. -1-, it may beseen that to assemble acore-takingl projectile embodying the present invention, cutting ring 24is merely placed` so that recess 25 engages seat 21,` 22 of core barrel18 and the retainer 30 simply may be stretched to receive the `cuttingring and-the lcore barrel. The retainer may then be released so,` thatit fallsY into the position illustrated in Fig. 1. lf desired, asuitable lubricant may be used to facilitate the positioning of theretainer. Obviously, for a secure spatial association of the elements,the diameter of retainer 30, prior to the assembly of the elements,should be somewhat smaller than illustrated in lFig. 1. i

ln operation gun block` including a sample-taking projectile 17embodying the presentinvention is lowered into borehole 11 to a positionopposite` the formation of interest 12 as illustrated in Fig. l.Retainer 30 holds the cutting ring24 in a xed position with respect tocore barrel 18 during descent. l

, At the desired depth, propellant 16 is ignited, and the projectile 17is impelled toward the sidewall of the borehole 1-1. During this portionof an operating cycle, cutting ring 24 remains in a fixed positionrelativeto core barrel 18 with recess 25 on seat 21, 22. A

As the projectile enters the formation, .forward face .34 of retainer 30engages formation material so that continued movement of the projectileeffects relative displacement of the retainer; The retainer thus isdisplaced to a position illustrated in Fig. 2 during the phase ofoperation in which core barrel 18 receives a core sample 40. In someinstances, the passage of the projectile 17 through mud 13 `causesrelative displacement of the retainer 30. v Y Since cutting ring 24 cutsan oversize hole 41 inearth formations 1,2, and' no` longer is attachedto core barrel 18 because of the movement of retainerti, the core barreltogether with the core sample 40 may be withdrawn from the formationwhile cutting ring 24 remains embedded therein. This is done by drawingupwardly on `gun block 10, motion being imparted to the core barrel V18by means of retrieving wires 35 and 35.". Thus, the core barrel may bebrought to the surface and the sample 4t).A can be examined. Y 4 Y It isobvious from the foregoing discussionthatvin a formation-samplingprojectile embodying the present invention, the possibility ofpremature, inadvertent separation between the retaining ring and the`core barrel .is minimized., However, after a core sample is obtained,

, the core barrel and cutting ring are easily separated.

Furthermore, it is evident that a projectile embodying `the presentinvention is simple and inexpensive to construct. Therefore, aprojectile embodying the present invention aifords an important advanceover prior devices of this type.

While a particular embodlment of the presentinvention has been shown anddescribed, it is apparent that changes and modifications may be madewithout departing from this invention in its broader aspects, andtherefore the aim in the appended claims is to cover all such changesand modifications as fall within the true spiritand scope of thisinvention. i

I claim: v

l. Apparatus for investigating earth formations comprising'core-receiving and formation-penetrating members disposed adjacent oneanother in end-to-end relation Vand adapted to be impelled toward ,aformation and `embedded therein, ,th'e outer diameter of saidformationpenetrating member being greater than the outer diameter ofsaid core-receiving member and the end or" said formation-penetratingmember that extends `away from said core-receiving member being in theshape of a cutting edge, and a hollow retainer of resilient materialincluding means for receiving adjacent portions of each of saidcore-receiving `and said formation-penetrating members to maintain saidmembers essentially iixed in relation to one another, but releasablefrom at least said formation penetrating member thereby to permitWithdrawal of said core-receiving member .from the formation while saidformation-penetrating member remains embedded therein.

2. Apparatus Ifor investigating` earth formations comprisingcore-receiving and formation-penetrating members disposed adjacent oneanother in end-to-end relation andadapted to be impelled along alongitudinal axis of said members toward a formation and embeddedtherein, the outer diameter of said formation-penetrating.member beinggreater than the outer diameter of said corereceiving member and the endof said formation-penetrating member that extends away from saidcore-receiving member being of a generally frusto-conical configurationconverging away from said core-receiving member to provide a cuttingedge, and a Ahollow retainer of resilient material includingmeansforreceiving adjacentportions ofk each of said core-receiving and saidformation-penetrating members to ,maintain said members essentially'fixed in relation to one another,V but releasable `from at least saidAformation penetrating member, said retainer t including a forwardsurface near the forward end of said formation penetrating memberdisposed in a plane substantially transverse to said longitudinal axisand extending laterally outwardly from said members, saidsurface beingadapted to engage formation material and effect release of said retainerfrom 4said one member Vthereby to permit withdrawal ofsaidcore-receiving member from the 4formation while saidformation-penetrating member remains embedded therein.

3. Apparatus for investigating earth formations comprising ahollow'core-receivingmember adapted to be impelled toward a 4formationand having .al forward end, a formation-penetrating member having acutting edge disposedadjacentsaid forward end of said core-receivingmember and in end-,to-cnd relationship tl1erewith,'means adapted toimpelsad core-receiving member in the direction of said forward end intoaformation, and a hollow retainer of resilient material including meansfor receiving adjacent portionsfofjeach of said core-receiving and saidformation-penetrating rnembersqto` maintain `said members in essentiallylixed relation to one another, but releasable from at least saidformation penetrating member thereby to permit withdrawal ofV saidcore-receiving memberfrom the formation while.saidformation-penetrating`member remain's embedded therein.

4.V Apparatus forV investigating wearth formations icomprising a hollowcore-receiving member adapted to be impelledtoward a formationand'having a forward end and an annular recess in `the `vicinity of saidforward end, a formationepenetratirig member having a cutting edgedisposed adjacent said forward end of said core-receiving Ymember inend-to-end relation therewith, means adapted Ycore-receiving member fromthe formationwhilesaid formation-penetrating member remains embeddedvtherein.

5. Apparatus for investigating earth formations comprlsing' a-hollow`core-receiving member adapted `to be .impelled toward `a formation andhaving forward end, `an `annular formation-penetrating member having acut-` ting edge disposed adjacent'sai'd'- forward `end of saidcore-receiving member in end-to-end` relation therewith and-having anexternal ,surface Vof `generally frusto-coni- .-calcongurationconverging forwardly from said forward end of said core-receivingmember, and an annular retainer of resilient material including meansfor receiving adjacent portions of each of said core-receiving and saidformation-penetrating members and having an internal surfacesubstantially conforming to the configuration of said generallyfrusto-conical surface of said formationpenetrating member, saidretainer further including means for maintaining said members inessentially fixed relation to one another, but releasable from at leastsaid formation penetrating member thereby to permit withdrawal of saidcore-receiving member from the formation while saidformation-penetrating member remains embedded therein.

6. Apparatus for investigating earth formations comprising a hollowcore-receiving member having a forward end, including a forward portionof a given area in a plane transverse to a longitudinal axis for saidmember, and being adapted to be impelled toward a formation, aformation-penetrating member having a cutting edge disposed adjacentsaid forward end of said core-receiving member in end-to-end relationtherewith and having a rearward portion in a plane transverse to saidlongitudinal axis of an area larger than and overlying said given area,and a hollow retainer of resilient material including means forreceiving adjacent portions of each of said core-receiving and saidformation-penetrating members to maintain said members in essentiallyfixed relation to one another, but releasable from at least saidformation penetrating member thereby to permit withdrawal of saidcore-receiving member from the formation while saidformation-penetrating member remains embedded therein.

7. Apparatus for investigating earth formations comprising asubstantially cylindrical, hollow core barrel adapted to be impelledtoward a formation along a longi- 6 tudnal axis of said core barrel andincluding a forward end defining a seat and an outer cylindrical surfaceportion having an annular recess disposed in the vicinity of saidforward end, a substantially cylindrical cutting ring including arearward end cooperating with and engaging Said seat of said core barreland an external surface of generally frusto-conical configurationextending forwardly from said rearward end and inwardly toward saidlongitudinal axis and forming a cutting edge, and a substantiallycylindrical hollow retainer of resilient material 'eceiving portions ofsaid core barrel and said cutting ring, including an inner surfacehaving a ridge extending inwardly into said recess of said core barreland having a portion conforming to and engaging at least a portion ofsaid external surface of generally frusto-conical configuration of saidcutting ring to maintain said core barrel and said cutting ring inessentially fixed relationship to one another, and said retainer furtherincluding a forward surface near the forward surface of said formationpenetrating means disposed in a plane substantially transverse to saidlongitudinal axis extending laterally outwardly from said members, saidsurface being adapted to engage formation material so that continuedmovement of said cutting ring in a forward direction effects relativedisplacement between said cutting ring and said retainer thereby topermit withdrawal of said core barrel from the formation while saidcutting ring remains embedded therein.

eferences Qited in the file of this patent UNITED STATES PATENTS LeoneDec. 25, 1956

